64 50 ... A/C Efficiency Test (R 134a)

64 50 ... - A/C efficiency test (R 134a)

Observe the following conditions prior to the A/C efficiency test:
1. - Provide a MoDiC or DIS. Safeguard electrical system integrity by checking the fault memory (no faults in the fault memory).

2. - Provide a thermometer with separate gauge.

3. - Perform the test in a suitable work bay with an ambient temperature between 20 °C and 30 °C.

Re 1:
Connect diagnosis system to vehicle and display evaporator temperature.
Re 2:
Position a thermometer with a separate gauge approx. 5 cm below the roof liner at the height of the B-pillar. Lay gauge outwards out of vehicle interior.
Re 3:
Heat vehicle interior:
- "A/C button" is not activated during the heating process

- Close all windows and doors.

- Set recirculated air mode.

- In A/C menu (MMI) in Air distribution index tab: select 100 % footwell for driver and front passenger and 100 % defrosting for driver (this applies here to driver and front passenger)

- Maximum temperature setting (28 °C)

- Maximum fan speed (adjust 9 pixels from 9 possible on front A/C control panel)

- Run engine at approx. 2000 rpm until operating temperature is reached, then idle speed.

A/C efficiency test:
Turn on A/C compressor via "A/C button" at a vehicle interior temperature of 50 °C.
Vehicles with MAX-AC button ("MAX"):
- Activation of MAX-AC (= maximum chilling capacity)

Vehicles without MAX-AC button ("MAX"):
- Set maximum chilling capacity by means of following steps:

- Temperature setting = 16 °C

- Fan setting 9 pixels from 9 possible

- Stratification maximum cold (4 blue bars)

Evaporator sensor temperature must be ≤ 15 °C after 3-4 minutes at approx. 2000 rpm.
Draw off A/C system 64 50 009 Drawing Off, Evacuating and Filling A/C System (R 134a) if this temperature is not reached. Measure amount of refrigerant drawn off.
If drawn-off quantity does not correspond to specified fill quantity: supplement refrigerant and repeat test.
If fill quantity is correct, continue troubleshooting by pressure measurement.